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Torque Due to Weight quiz

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  • Where does the weight force (mg) act on an object with uniform mass distribution?
    It acts at the object's geometric center, which is the center of gravity or center of mass.
  • What is the formula for torque due to a force?
    Torque = force x distance x sin(theta), where theta is the angle between the force and the lever arm.
  • How do you determine the distance (r) for the torque calculation of a rod's weight?
    For a rod with uniform mass distribution, r is half the length of the rod, measured from the axis to the center.
  • If a rod is 4 meters long, where does its weight force act?
    It acts at 2 meters from either end, right at the middle of the rod.
  • What is the difference between center of gravity and center of mass in most physics problems?
    They are usually the same unless the gravitational field is not uniform.
  • What angle should you use in the torque formula if the rod makes 37 degrees with the horizontal?
    You should use 53 degrees, which is 90 minus 37, as the angle between the force and the lever arm.
  • How do you calculate the torque produced by a person standing at the end of the rod?
    Use the person's weight (mg), the full length of the rod as r, and the correct angle in the torque formula.
  • What is the sign of the torque if the force causes counter-clockwise rotation?
    The torque is considered positive.
  • How do you find the net torque when multiple forces act on the rod?
    Add the individual torques, considering their signs (positive or negative).
  • What is the net torque produced in the example with a 20 kg rod and an 80 kg person?
    The net torque is 2817 Newton meter, positive, indicating counter-clockwise rotation.
  • Why is it important to know how to calculate torque due to weight?
    Because it appears frequently in physics problems involving rotation and equilibrium.
  • What happens if the rod does not have uniform mass distribution?
    The center of gravity may not be at the geometric center, and you must use the actual center of gravity for torque calculations.
  • What is the value of gravity (g) used in the example calculations?
    Gravity is rounded to 10 m/s² for simplicity.
  • What is the torque produced by the rod's own weight in the example?
    It is 313 Newton meter, positive.
  • What is the torque produced by the person's weight in the example?
    It is 2504 Newton meter, positive.